In recent years, pick-up toppers have become popular and appear on the market in a variety of different shapes, models and designs, such as campers, caps and cabs. These units are lifted onto the truck bed and anchored to the truck box by clamp assemblies or other types of holddown brackets.
Pick-up truck boxes include a bottom wall, sidewalls, an end wall and a tailgate with the wheel wells projecting into the box. The tops of the sidewalls extend inwardly toward each other, thus forming opposing transverse flanges which are disposed over the bottom wall of the truck box. The design of the sidewalls and the transverse flanges for each manufacture, however, are different, thus necessitating a plurality of different clamp assemblies or holddown brackets to supply the market.
A clamp assembly for securing a topper onto the pick-up truck box must be robust to prevent the topper from bouncing off the truck box while travelling on rough terrain, sliding off the box when travelling up a hill, or from sliding or slamming into the end wall and cab of the truck when travelling downhill or in the event of a sudden stop. The clamp assembly is also expected to be simple for operating, easily accessible for securing the topper to or releasing it from the pick-up truck box because the pick-up truck may be used for other purposes.
Prior art has focused on those objects and various types of clamp assemblies, holddown brackets or locking devices have been created. U.S. Pat. No. 3,503,647, entitled CAMPER HOLDDOWN BRACKET and issued to Gostomski on Mar. 31, 1970, for example, describes a universal camper holddown bracket for securing a camper to the bed of a pick-up truck having lipped sidewalls. In response to a movement of a slidable rod, an arm is pivotable from a non-locking engagement to a locking engagement with the lip, and enabled to be locked in the locking engagement position. The slidable rod, however, is operated from the outer side of the camper. This is somehow a disadvantage in respect to security considerations.
Another example is described by Thibault in his Canadian Patent No. 2,083,300 which is entitled QUICK-RELEASE LOCK FOR PICK-UP TRUCK TOPPER and issued Feb. 3, 1998. Thibault describes a pivotal handle bar assembly including a removable pivotable handle, projecting inside the topper enclosure, and a fulcrum end with an elastomeric pad to frictionally anchor the topper to the truck box. Release of the handle bar lock is possible only from within the topper enclosure. The elastomeric pad, however, is not durable and too soft to firmly secure the topper to the truck box, particularly under vibration and impact when the vehicle travels on rough terrain. Another disadvantage relates to the manner and structure for adjusting the distance from the fulcrum end to the pivot pin in order to fit in with the needs of vehicles of different makes and models. A telescoping tubing structure with locking pin is used to adjust the length of the pivotal handle bar, which has to be manually down before the assembly is installed to the topper.
Practically, a topper is usually anchored onto the pick-up truck box at four points, that is, a front place and a rear place at each side. Four identical clamp assemblies are used and operated individually one after another to lock the topper to the truck box. The structural rigidity of the topper and the pick-up truck box are different since the topper is usually an enclosure structure such as a cab or camper, while the truck box is an open structure. When the vehicle travels on rough terrain, the pick-up truck box may be instantly twisted to an extent that the relatively rigid cab or camper cannot follow the instant deformation of the pick-up truck box and, therefore, tension is resulted to break the clamp assemblies.
There therefore exists the need for continuous improvements of clamp assemblies for use in such applications.